U.S. Pat. No. 3,810,482, which is assigned to the assignee of the present invention (the '482 Patent), describes a tent having the characteristics set forth in the previous section. The '482 Patent describes a collapsible tent comprising three side walls arranged at approximately right angles to each other and a top wall, i.e., a roof. Each panel consists of a rectangular or trapezoidal panel of tent fabric and a frame, connected with the covering at its corners. Each frame consists of a hub and four frame rods or struts hingable in a plane perpendicular to the hub, the frame rods or struts being hingable and collapsible to a position in which they are parallel to each other and approximately perpendicular to the hub. The struts are hingable from this position through an angle exceeding 90.degree. from their original position and beyond a "dead center" in which the rods are in one plane. In the tent of the '482 Patent, stretchable cords are attached along the edge forming the perimeter of each panel, which cords are tied together at the corners of the panel, such that an endless loop is formed around each panel, which is constantly under tensile stress, when the tent is erected. The tent has been widely accepted in the industry for a number of reasons, including the fact that the tent is easy to erect and take down, it is compact and light weight for convenient storage and transportation, and it is durable.
Nevertheless, a significant drawback to the tent shown in the '482 Patent tent is the difficulty in stabilizing it when three or fewer panels are employed. This is particularly true in larger sizes. By tensioning the stretchable cords and tying them together, essentially only the corners of the tent cloth panel are pulled towards each other in circumferential direction, as a result of which the tent cloth between the corners will sag.
The problem is most extreme when attempting to construct a shelter using a single panel (comprising hub, struts and covering) as a roof which is supported by a number of vertical legs. Such a structure, an example of which is generally depicted in FIG. 1, is useful as a "hospitality" tent for social functions or in work environments where easy entrance to and egress from the shelter are desired. However, such a structure is quite unstable. The roof struts and vertical legs tend to twist with respect to one another, and the roof struts tend to twist with respect to the hub. In addition, there is a tendency for the hub to pass back through center resulting in the collapse of the roof frame. Various forces, such as the wind, inadvertent contact with a support leg, or other sudden forces can add to the risk of twisting and hub collapse. Such a structure is both precarious and unattractive.
As previously noted, open-sided tents are frequently used for hospitality purposes where it is desirable for people to move in and out of a tent easily on more than one side. To resolve the problems noted in the previous paragraph, caterers and others in the party rental business have resorted to using very heavy, durable components for the structure especially the legs, struts and hinges or other connecting means. Even then, the bottom of the legs or other structural elements are staked to the ground to provide further stability. Although these tents are stable, they are heavy, difficult to move and store, and require a considerable amount of time and effort to erect and disassemble. Numerous separate components are involved that can get lost or mislaid. Such tents are totally unsuited for work environments where it is highly desirable to have a stable, light weight open-sided shelter that is quickly erected and taken down and easily transported and stored.